But, this may not last long as more states and cities create protections for their overweight workers.

Scott's Miracle-Grow company is charging employers higher insurance premiums if they refuse to take part in health-assessments or work with company-supplied health coaches. But, programs like Scott's are facing backlash.

"Employers have the potential to engage in discrimination if they are telling people that they need to lose weight or engage in other activities based on assumptions and stereotypes," said Lisa Tealer with the Association to Advance Fat Acceptance.

Some overweight employees fear employer crackdowns only enforce negative stereotypes. 43% say employers or supervisors exhibit bias against them. 54% report they are stigmatized by their own co-workers.

Studies show the negative impact on employers is growing. Nearly 39 million workdays are lost every year in connection with obesity. The number coupled with medical expenditures for obese employees, amounts to a cost of $45 billion a year for U.S. employers.

"This is a cost analysis, not a morality issue, not a stigmatization issue," said Meme Roth with National Action Against Obesity. "This is cost analysis, employers are pushed up against the wall. They absolutely have to take action. If somebody is a more expensive employee, then employers have to do something about that."

As wellness programs and employee surcharges multiply, employers are acutely aware of the legal tightrope they must walk. In Washington, D.C. personal appearance is a protected category. In San Francisco weight and height are protected traits.

"There are privacy interests as well," said Lynn Argenbright, an employer benefits advisor. "An employee could say, 'You are impacting my privacy. You are invading my privacy by trying to tell me what to do when I'm not at work.'"

A recent survey shows 40% of United States companies have started obesity-reduction programs, with another 24% reporting they will soon adopt them.